United States 

Environmental Protection Agency 

Office of Water 

4305T 

EPA-823-R-06-008

October 2006

AQUATOX (RELEASE 2.2): MODELING 

ENVIRONMENTAL FATE AND ECOLOGICAL EFFECTS 

IN AQUATIC ECOSYSTEMS: 

Technical Documentation (addendum)

Background 

Minor changes have been made to the AQUATOX model since Release 2.1 was publicly 

released. This document describes changes in the model that distinguish Release 2.2 from 

Release 2.1 and describes any changed equations. 

What’s New 

• AQUATOX now outputs retention time of a waterbody: 

Retention=Volume / (1b) Discharge

where: 

Retention = retention time for water body (d) 

Volume = current volume of water (m3), 

Discharge = discharge of water from waterbody (m3/d), and 

• There has been a refinement in the way that the light extinction due to blue-greens is 

calculated that improves the calculation of self-shading and improves simulations of 

blue-greens overall. 

o When calculating self-shading for blue-greens, the model accounts for more 

intense self shading in the upper layer of the water column due to the floating 

concentration of blue-greens there. 

o The Extinction term for blue-greens (within equation (34) from the AQUATOX 

Release 2 Technical Documentation) is multiplied by the segment thickness and 

divided by the thickness over which blue-greens occur to account for the more 

intense self-shading effects of these blue greens concentrated at the top of the 

water. 

• AQUATOX now calculates, as an additional index, blue-greens as a percentage of the 

total phytoplankton biomass 

• AQUATOX now utilizes mean velocity rather than daily velocity when calculating 

“Adaptation” for sloughing velocity (see equation (3a) from the AQUATOX Release 2.1 

Technical Documentation Addendum) 

o In Release 2.1, a unique Adaptation was calculated for each time-step depending 

on the mean velocity on that day. 
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o In Release 2.2, a constant Adaptation is calculated using code that calculates the 

site’s mean velocity on an annual basis. 

o Using a constant value was the original intent for the Adaptation factor and this 

change should improve the model’s capabilities to simulate periphyton across 

sites. 

• AQUATOX Release 2.1 (and previous versions) errantly under-calculated the effects of 

excess temperature in plants. 

o The mortality effects of excess temperature in plants should slowly increase up 

until 100% mortality is achieved at the maximum temperature (TMax) level. (see 

equation (59) and Figure 39 from the AQUATOX Release 2 Technical 

Documentation) 

o Release 2.1 (and previous versions) had a coding error in which excess 

temperature effects were not calculated until TMax was exceeded. That equation 

error has been fixed in Release 2.2. 

o This has had a negligible effect on existing AQUATOX calibrations as 

temperatures approaching and exceeding the TMax for various species were rarely 

encountered, and temperature limitations on photosynthesis adequately captured 

the majority of these effects. 

• An error has been fixed in which initial conditions for phosphate and nitrate, when 

entered in units of Total P and Total N, were not calculated properly. 

o There was an error in the back-calculation of the amount that is available as freely 

dissolved nutrients by accounting for the nitrogen and phosphorus contributed by 

suspended and dissolved detritus and phytoplankton. 

o This had no effects on the existing set of calibrated study files. 

• Release 2.2 contains an improved algal parameter set (Plant “Library”) and the 

calibration of many of the enclosed study files has been improved. 

• There have been small refinements made to the display of output graphs (e.g. when 

examining output on a very small scale, Y1 and Y2 axis labels no longer disappear). 

• AQUATOX output units have been clarified with regard to wet or dry weight. 

• There is an improved Graphical User Interface (GUI) to more easily assign toxicity data, 

by allowing a user to map links between chemicals and biota within a single entry screen 

(see the “Edit All Toxicity Records” button within animal and plants “underlying data”). 

• When adding a new animal or plant, a small "seed" loading is added by default to avoid 

extinctions (1E-5 mg/L or g/m2

). 

• The help file has been updated to correct several light conversion factors (used when 

inputting light loadings to AQUATOX). 

• Release 2.2 includes several minor interface refinements (e.g. units were clarified for 

loadings in the “Suspended and dissolved detritus” entry screen in terms of dry vs. wet 

weight as well as organic matter vs. organic carbon or BOD) 

Other Changes to AQUATOX Technical Documentation 

In the second printing of the Release 2 Technical Documentation (EPA-823-R-04-002, with a 

blue cover) two tables were missing entries due to a software conversion problem in the printing 

process. The following tables should be inserted on p. 4-1: 
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Table 3. Significant Differentiating Processes for Plants 

Plant Type Nutrient 

Lim.

Current 

Lim.

Sinking Washout Sloughing Breakage Habitat

Phytoplankton ♦ ♦ ♦ ♦ 

Periphyton ♦ ♦ ♦ ♦ 

Macrophytes ♦ ♦ 

Bryophytes ♦ ♦ ♦ 

 

Table 4. Significant Differentiating Processes for Animals 

Animal Type Washout Drift Entrainment Emergence Promotion Multi-year

Pelagic 

Invert. 

♦ 

Benthic 

Invert. 

 ♦ ♦ 

Benthic Insect ♦ ♦ ♦ 

Fish ♦ ♦ ♦ 

The following are citations missing from the References section of the Release 2 and 2.1 

Technical Documentation: 

Hanson, Paul C., Timothy B. Johnson, Daniel E. Schindler, and James F. Kitchell. 1997. Fish 

Bioenergetics 3.0. Madison: Center for Limnology, University of Wisconsin. 

Sterner, Robert W., and Nicholas B. George. 2000. Carbon, Nitrogen, and Phosphorus 

Stoichiometry of Cyprinid Fishes. Ecology 81:127-140. 

The Release 2.1 Technical Documentation Addendum omitted Appendix B (a list of AQUATOX 

parameters). The following is the complete and updated Appendix B: 
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APPENDIX B. USER-SUPPLIED PARAMETERS AND DATA  The model has many parameters and internal variables. Most of these are linked to data structures such as ChemicalRecord, SiteRecord, and turn may be linked to input forms that the user accesses through the Windows environment. Although consistency has been a goal, some names may d

user interface, and the technical documentation USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

 ChemicalRecord Chemical 

Underlying Data 

For each chemical simulated, the following parameters are required 

Chemical ChemName N / A chemical's Name. Used for Reference only. CAS Registry No. CASRegNo N / A CAS Registry Number. Used for Reference only. Molecular Weight MolWt MolWt molecular weight of pollutant Dissociation Constant pka pKa acid dissociation constant Solubility Solubility N / A Not utilized as a parameter by the code. Henry's Law Constant Henry Henry Henry's law constant Vapor Pressure VPress N / A Not utilized as a parameter by the code. Octanol-water partition coefficient 

LogP LogKow log octanol-water partition coefficient 

KPSED KPSed KPSed detritus-water partition coefficient Activation Energy for Temperature 

En En Arrhenius activation energy 

Rate of Anaerobic Microbial Degradation 

KMDegrAnaerobic KAnaerobic decomposition rate at 0 g/m3 oxygen 

Max. Rate of Aerobic Microbial Degradation 

KMDegrdn KMDegrdn maximum (microbial) degradation rate 

Uncatalyzed hydrolysis constant 

KUnCat KUncat the measured first-order reaction rate at pH 7 

Acid catalyzed hydrolysis constant 

KAcid KAcid pseudo-first-order acid-catalyzed rate constant for a give
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION Base catalyzed hydrolysis constant 

KBase KBase pseudo-first-order rate constant for a given pH 

Photolysis Rate PhotolysisRate KPhot direct photolysis first-order rate constant Oxidation Rate Constant OxRateConst N / A Not utilized as a parameter by the code. Weibull Shape Parameter Weibull_Shape Shape (Internal Model) parameter expressing variability in toxic response; defauWeibull Slope Factor WeibullSlopeFactor Slope Factor (External 

Model) 

slope at LC50 multiplied by LC50 

Chemical is a Base ChemIsBase if the compound is a base compound is a base 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

SiteRecord Site Underlying 

Data 

For each water body simulated, the followin

parameters are required 

Site Name SiteName N / A site's name- used for reference only Max Length (or reach) SiteLength Length maximum effective length for wave setup Vol. Volume Volume initial volume of site (must be copied into state var.) Surface Area Area Area site area Mean Depth ZMean ZMean mean depth, (initial condition if mean depth is selected) Maximum Depth ZMax ZMax maximum depth Ave. Temp. (epilimnetic or hypolimnetic) 

TempMean TempMean mean annual temperature of epilimnion (or hypolimnion) 

Epilimnetic Temp. Range (or hypolimnetic) 

TempRange TempRange annual temperature range of epilimnion (or hypolimnion

Latitude Latitude Latitude Latitude Average Light LightMean LightMean mean annual light intensity Annual Light Range LightRange LightRange annual range in light intensity Total Alkalinity AlkCaCO3 N / A Not utilized as a parameter by the code. Hardness as CaCO3 HardCaCO3 N / A Not utilized as a parameter by the code. Sulfate Ion Conc SO4Conc N / A Not utilized as a parameter by the code. Total Dissolved Solids TotalDissSolids N / A Not utilized as a parameter by the code. Limnocorral Wall Area LimnoWallArea LimnoWallArea area of limnocorral walls; only relevant to limnocorral Mean Evaporation MeanEvap MeanEvap mean annual evaporation Extinct. Coeff Water ECoeffWater ExtinctH2O light extinction of wavelength 312.5 nm in pure water Total Length TotalLength TotLength total river length for calculating phytoplankton retention Watershed Area WaterShedArea WaterShed watershed area for estimating total river length (above) 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

SiteRecord (StreamSpecific) Site Underlying Data For each stream simulated, the following parameters are required 

Channel Slope Channel_Slope Slope slope of channel Maximum Channel Depth Before Flooding 

Max_Chan_Depth Max_Chan_Depth depth at which flooding occurs 

Sediment Depth SedDepth SedDepth maximum sediment depth Stream Type StreamType Stream Type concrete channel, dredged channel, natural channel use the below value UseEnteredManning do not determine Manning coefficient from streamtype Mannings Coefficient EnteredManning Manning manually entered Manning coefficient. Percent Riffle PctRiffle Riffle percent riffle in stream reach Percent Pool PctPool Pool percent pool in stream reach  SiteRecord (Sand-SiltClay Specific) Site Underlying Data For each stream with the inorganic sedimen

model included, the following parameters arrequired 

Silt: Critical Shear Stress for Scour 

ts_silt TauScourSed critical shear stress for scour of silt 

Silt: Critical Shear Stress for Deposition 

tdep_silt TauDepSed critical shear stress for deposition of silt 

Silt: Fall Velocity FallVel_silt VTSed terminal fall velocity of silt Clay: Critical Shear Stress for Scour 

ts_clay TauScourSed critical shear stress for scour of clay 

Clay: Critical Shear Stress for Deposition 

tdep_clay TauDepSed critical shear stress for deposition of clay 

Clay: Fall Velocity FallVel_clay VTSed terminal fall velocity of clay 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

ReminRecord Remineralization 

Data 

For each simulation, the following paramete

required (pertaining to organic matter) 

Max. Degrdn Rate, labile DecayMax_Lab DecayMax maximum decomposition rate Max Degrdn Rate, Refrac DecayMax_Refr ColonizeMax maximum colonization rate under ideal conditions Temp. Response Slope Q10 Q10 Not utilized as a parameter by the code. Optimum Temperature TOpt TOpt optimum temperature for degredation to occur Maximum Temperature TMax TMax maximum temperature at which degradation will occur Min. Adaptation Temp TRef TRef Not utilized as a parameter by the code. Min pH for Degradation pHMin pHMin minimum pH below which limitation on biodegradation 

occurs. 

Max pH for Degradation pHMax pHMax maximum pH above which limitation on biodegradation 

occurs. 

P to Organics, Labile P2OrgLab P2OrgLab ratio of phosphate to labile organic matter N to Organics, Labile N2OrgLab N2OrgLab ratio of nitrate to labile organic matter P to Organics, Refractory P2OrgRefr P2OrgRefr ratio of phosphate to refractory organic matter N to Organics, Refractory N2OrgRefr N2OrgRefr ratio of nitrate to refractory organic matter P to Organics, Diss. Labile P2OrgDissLab P2OrgDissLab ratio of phosphate to dissolved labile organic matter N to Organics, Diss. Labile N2OrgDissLab N2OrgDissLab ratio of nitrate to dissolved labile organic matter P to Organics, Diss. Refr. P2OrgDissRefr P2OrgDissRefr ratio of phosphate to dissolved refractory organic matter N to Organics, Diss. Refr. N2OrgDissRefr N2OrgDissRefr ratio of nitrate to dissolved refractory organic matter O2 : Biomass, Respiration O2Biomass O2Biomass ratio of oxygen to organic matter O2: N, Nitrification O2N O2N ratio of oxygen to nitrogen Detrital Sed Rate (KSed) KSed KSed intrinsic sedimentation rate PO4, Anaerobic Sed. PSedRelease N / A Not utilized as a parameter by the code. NH4, Aerobic Sed. NSedRelease N / A Not utilized as a parameter by the code. 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION Wet to Dry Susp. Labile Wet2DrySLab Wet2DrySLab wet weight to dry weight ratio for suspended labile detritWet to Dry Susp. Refr. Wet2DrySRefr Wet2DrySRefr wet weight to dry weight ratio for suspended refractory dWet to Dry Sed. Labile Wet2DryPLab Wet2DryPLab wet weight to dry weight ratio for particulate labile detritWet to Dry Sed. Refr. Wet2DryPRefr Wet2DryPRefr wet weight to dry weight ratio for particulate refractory d
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION  ZooRecord Animal Underlying 

Data 

For each animal in the simulation, the followparameters are required 

Animal AnimalName N / A animal's name- used for reference only Animal Type Animal_Type Animal Type animal type (Fish, Pelagic Invert, Benthic Invert, Benthic Taxonomic Type or Guild Guild_Taxa Taxonomic type or guild Taxonomic type or trophic guild Toxicity Record ToxicityRecord N / A associates animal with appropriate toxicity data Half Saturation Feeding FHalfSat FHalfSat half-saturation constant for feeding by a predator Maximum Consumption CMax CMax maximum feeding rate for predator Min Prey for Feeding BMin BMin minimum prey biomass needed to begin feeding Temp Response Slope Q10 Q10 slope or rate of change in process per 10°C temperature cOptimum Temperature TOpt TOpt optimum temperature for given process Maximum Temperature TMax TMax maximum temperature tolerated Min Adaptation Temp TRef TRef adaptation temperature below which there is no acclimatEndogenous Respiration EndogResp EndogResp basal respiration rate at 0° C for given predator Specific Dynamic Action KResp KResp proportion assimilated energy lost to specific dynamic acExcretion:Respiration KExcr KExcr proportionality constant for excretion:respiration N to Organics N2Org N2Org ratio of nitrate to organic matter for given species P to Organics P2Org P2Org ratio of phosphate to organic matter for given species Wet to Dry Wet2Dry Wet2Dry ratio of wet weight to dry weight for given species Gamete : Biomass PctGamete PctGamete fraction of adult predator biomass that is in gametes Gamete Mortality GMort GMort gamete mortality Mortality Coefficient KMort KMort intrinsic mortality rate Carrying Capacity KCap KCap carrying capacity 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION Average Drift AveDrift Dislodge fraction of biomass subject to drift per day VelMax VelMax VelMax maximum water velocity tolerated Mean lifespan LifeSpan LifeSpan mean lifespan in days Initial fraction that is lipid FishFracLipid LipidFrac fraction of lipid in organism Mean Weight MeanWeight WetWt mean wet weight of organism Percent in Riffle PrefRiffle PreferenceHabitat percentage of biomass of animal that is in riffle, as oppos

or pool 

Percent in Pool PrefPool PreferenceHabitat percentage of biomass of animal that is in pool, as oppos

or riffle 

Fish spawn automatically, based on temperature range 

AutoSpawn does AQUATOX calculate spawn dates 

Fish spawn of the following dates each year 

SpawnDate1..3 user entered spawn sates 

Fish can spawn an unlimited number of times... 

UnlimitedSpawning allow fish to spawn unlimited times each year 

Fish can only spawn... SpawnLimit number of spawns allowed for this species this year Use Allometric Equation to Calculate Maximum Consumption 

UseAllom_C use allometric consumption equation 

Intercept for weight dependence 

CA allometric consumption parameter 

Slope for weight dependence CB allometric consumption parameter Use Allometric Equation to Calculate Respiration 

UseAllom_R use allometric consumption respiration 

RA RA intercept for species specific metabolism RB RB weight dependence coefficient 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION Use “Set 1" of Respiration Equations 

UseSet1 use "set 1" of allometric respiration parameters 

RQ RQ RQ allometric respiration parameter RTL RTL RTL temperature below which swimming activity is an expon

function of temperature 

ACT ACT ACT intercept for swimming speed for a 1g fish RTO RTO RTO coefficient for swimming speed dependence on metaboliRK1 RK1 RK1 intercept for swimming speed above the threshold tempeBACT BACT BACT coefficient for swimming at low temperatures RTM RTM not currently used as a parameter by the code RK4 RK4 RK4 weight-dependent coefficient for swimming speed ACT ACT intercept of swimming speed vs. temperature and weight Preference (ratio) TrophInt.Pref[ ] Prefprey,pred initial preference value from the animal parameter screen Egestion (frac.) TrophInt.Egest[ ] EgestCoeffprey,pred fraction of ingested prey that is egested 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

PlantRecord Plant Underlying 

Data 

For each Plant in the Simulation, the followparameters are required 

Plant PlantName plant's name- used for reference only Plant Type PlantType Plant Type plant type: (Phytoplankton, Periphyton, Macrophytes, BrTaxonomic Group Taxonomic_Type Taxonomic Group taxonomic group Toxicity Record ToxicityRecord N / A associates plant with appropriate toxicity data Saturating Light LightSat LightSat light saturation level for photosynthesis P Half-saturation KPO4 KP half-saturation constant for phosphorus N Half-saturation KN KN half-saturation constant for nitrogen Inorg C Half-saturation KCarbon KCO2 half-saturation constant for carbon Temp Response Slope Q10 Q10 slope or rate of change per 10°C temperature change Optimum Temperature TOpt TOpt optimum temperature Maximum Temperature TMax TMax maximum temperature tolerated Min. Adaptation Temp TRef TRef adaptation temperature below which there is no acclimatMax. Photosynthesis Rate PMax PMax maximum photosynthetic rate Photorespiration Coefficient KResp KResp coefficient of proportionality between. excretion and 

photosynthesis at optimal light levels 

Resp. Rate at 20 deg. C Resp20 Resp20 respiration rate at 20°C Mortality Coefficient KMort KMort intrinsic mortality rate Exponential Mort Coeff EMort EMort exponential factor for suboptimal conditions P to Organics P2Org P2Org ratio of phosphate to organic matter for given species N to Organics N2Org N2Org ratio of nitrate to organic matter for given species Light Extinction ECoeffPhyto EcoeffPhyto attenuation coefficient for given alga Wet to Dry Wet2Dry Wet2Dry ratio of wet weight to dry weight for given species 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION Phytoplankton: Sedimentation Rate 

KSed KSed intrinsic settling rate 

Phytoplankton: Exp. Sedimentation Rate 

ESed ESed exponential settling coefficient 

Carrying Capacity N / A N / A Not utilized as a parameter by the code. Periphyton: Reduction in Still Water 

Red_Still_Water RedStillWater reduction in photosynthesis in absence of current 

VelMax for macrophytes Macro_VelMax VelMax velocity at which total breakage occurs Periphyton: Critical Force (FCrit) 

FCrit FCrit critical force necessary to dislodge given periphyton grou

Percent in Riffle PrefRiffle PrefRiffle percentage of biomass of plant that is in riffle, as oppose

pool 

Percent in Pool PrefPool PrefPool percentage of biomass of plant that is in pool, as opposed 

riffle 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

AnimalToxRecord Animal Toxicity 

Parameters 

For each Chemical Simulated, the following parameters are required for each animal sim

LC50 LC50 LC50 concentration of toxicant in water that causes 50% mortaLC50 exp time (h) LC50_exp_time ObsTElapsed exposure time in toxicity determination K2 Elim rate const K2 K2 elimination rate constant K1 Uptake const K1 K1 uptake rate constant, only used if “Enter K1” option is seBCF BCF BCF Bioconcentration factor, only used if “Enter BCF” option 

selected 

Biotrnsfm rate BioRateConst BioRateConst percentage of chemical that is biotransformed to 

specific daughter products

EC50 growth EC50_growth EC50Growth external concentration of toxicant at which there is a 50% 

reduction in growth 

Growth exp (h) Growth_exp_time ObsTElapsed exposure time in toxicity determination EC50 repro EC50_repro EC50Repro external concentration of toxicant at which there is a 50% 

reduction in reprod 

Repro exp time (h) Repro_exp_time ObsTElapsed exposure time in toxicity determination Ave. wet wt. (g) Ave_wet_wt WetWt mean wet weight of organism Lipid Frac Lipid_frac LipidFrac fraction of lipid in organism Drift Threshold (ug/L) Drift_Thresh Drift Threshold concentration at which drift is initiated  TPlantToxRecord Plant Toxicity 

Parameter 

For each Chemical Simulated, the following parameters are required for each plant simu

EC50 photo EC50_photo EC50Photo external concentration of toxicant at which there is 50% 

in photosynthesis 

EC50 exp time (h) EC50_exp_time ObsTElapsed exposure time in toxicity determination 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION EC50 dislodge EC50_dislodge EC50Dislodge for periphyton only: external concentration of toxicant at 

there is 50% dislodge of periphyton 

K2 Elim rate const K2 K2 elimination rate constant K1 Uptake const K1 K1 uptake rate constant, only used if “Enter K1” option is seBCF BCF BCF bioconcentration factor, only used if “Enter BCF” option 

selected 

Biotrnsfm rate BioRateConst BioRateConst percentage of chemical that is biotransformed to 

specific daughter products

LC50 LC50 LC50 concentration of toxicant in water that causes 50% mortaLC50 exp.time (h) LC50_exp_time ObsTElapsed exposure time in toxicity determination Lipid Frac Lipid_frac LipidFrac fraction of lipid in organism  TChemical Chemical 

Parameters 

For each Chemical to be simulated, the folloparameters are required 

Initial Condition InitialCond Initial Condition initial condition of the state variable Gas-phase conc. Tox_Air Toxicantair gas-phase concentration of the pollutant Loadings from Inflow Loadings Inflow Loadings Daily loading as a result of the inflow of water Loadings from Point Sources Alt_Loadings[Pointsource] Point Source Loadings Daily loading from point sources Loadings from Direct Precipitation 

Alt_Loadings[Direct Precip] Direct Precipitation Load Daily loading from direct precipitation 

Nonpoint-source Loadings Alt_Loadings[NonPointsource] Non-Point Source Loading Daily loading from non-point sources Biotransformation BioTrans[ ] Biotransform percentage of chemical that is biotransformed to specific 

products 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION  TRemineralize Nutrient Parameters For each Nutrient to be simulated, O2 and C

the following parameters are required 

Initial Condition InitialCond Initial Condition initial condition of the state variable (TotP or TotN optio Loadings Inflow Loadings daily loading as a result of the inflow of water (TotP or T

optional) 

Loadings from Point Sources Alt_Loadings[Pointsource] Point Source Loadings daily loading from point sources Loadings from Direct Precipitation 

Alt_Loadings[Direct Precip] Direct Precipitation Loa daily loading from direct precipitation 

Non-point source loadings Alt_Loadings[NonPointsource] Non-Point Source Loading daily loading from non-point sources Fraction of Phosphate Available 

FracAvail fraction of phosphate loadings that is available versus tha

tied up in minerals 

TSedDetr Sed. Detritus 

Parameters 

For the Labile and Refractory Sedimented Detritus compartments, the following paramare required 

Initial Condition InitialCond Initial Condition initial condition of the labile or refractory sedimented deInitial Condition TToxicant.InitialCond Toxicant Exposure initial toxicant exposure of the state variable, for each chLoadings from Inflow Loadings Inflow Loadings daily loading of the sedimented detritus as a result of the 

water 

(Toxicant) Loadings TToxicant.Loads Tox Exposure of Inflow L daily parameter; toxicant exposure of each type of inflow

detritus, for each chemical 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION  TDetritus Susp & Dissolved 

Detritus 

For the Suspended and Dissolved Detritus compartments, the following parameters arrequired 

Initial Condition InitialCond Initial Condition initial condition of suspended & dissolved detritus, as o

matter, organic carbon, or biochemical oxygen demand 

Initial Condition: % Particulate 

Percent_Part_IC percent of initial condition that is particulate as opposed 

dissolved detritus 

Initial Condition: % Refractory 

Percent_Refr_IC percent of initial condition that is refractory as opposed t

detritus 

Inflow Loadings Loadings Inflow Loadings daily loading as a result of the inflow of water All Loadings: % Particulate Percent_Part Percent Particulate Infl daily parameter; % of all loadings that are particulate as 

to dissolved detritus 

All Loadings: % Refractory Percent_Refr Percent Refractory Inflo daily parameter; % of loading that is refractory as oppose

labile detritus 

Loadings from Point Sources Alt_Loadings[Pointsource] Point Source Loadings daily loading from point sources Nonpoint-source Loadings (Associated with Organic Matter) 

Alt_Loadings Non-Point Source Loading daily loading from non-point sources 

(Toxicant) Initial Condition TToxicant.InitialCond Toxicant Exposure initial toxicant exposure of the suspended and dissolved (Toxicant) Loadings (associated with Organic Matter) 

TToxicant.Loads Tox Exposure of Inflow 

Loading 

daily parameter; toxicant exposure of each type of inflowdetritus, for each chemical 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION  TBuried Detritus Buried Detritus For Each Type of Buried Detritus, the follo

parameters are required 

Initial Condition InitialCond Initial Condition initial condition of the labile and refractory buried detru(Toxicant) Initial Condition TToxicant.InitialCond Toxicant Exposure initial toxicant exposure of the labile and refractory burie

for each chemical simulated 

 TPlant Plant Parameters For each plant type simulated, the following 

parameters are required 

Initial Condition InitialCond Initial Condition initial condition of the plant Loadings from Inflow Loadings Inflow Loadings daily loading as a result of the inflow of water (Toxicant) Initial Condition TToxicant.InitialCond Toxicant Exposure initial toxicant exposure of the plant (Toxicant) Loadings TToxicant.Loads Tox Exposure of Inflow L daily parameter; toxicant exposure of the inflow loadings

chemical simulated 

TAnimal Animal Parameters For each animal type simulated, the followin

parameters are required 

Initial Condition InitialCond Initial Condition initial condition of the animal Loadings from Inflow Loadings Inflow Loadings daily loading as a result of the inflow of water (Toxicant) Initial Condition Ttoxicant.InitialCond Toxicant Exposure initial toxicant exposure of the animal (Toxicant) Loadings TToxicant.Loads Tox Exposure of Inflow L daily parameter; toxic exposure of the inflow loadings, f

chemical simulated 

Preference (ratio) TrophIntArray.Pref Prefprey, pred for each prey-type ingested, a preference value within the 

of preferences 

Egestion (frac.) TrophIntArray.ECoeff EgestCoeff for each prey-type ingested, the fraction of ingested prey 

egested 
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USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

TVolume Volume Parameters For each segment simulated, the following w

flow parameters are required 

Initial Condition InitialCond Initial Condition initial condition of the water volume . Water volume Volume Volume choose method of calculating volume; choose between m

equation, constant volume, variable depending upon inflodischarge, or use known values 

Inflow of Water InflowLoad Inflow of Water inflow of water; daily parameter, can choose between co

dynamic loadings 

Discharge of Water DischargeLoad Discharge of Water discharge of water; daily parameter, can choose between 

and dynamic loadings 

Site Characteristics Site Characteristics The following parameters are required 

Site Type SiteType Site Type site type affects many portions of the model. Site Mean Depth DynZMean user entered mean depth optional, time series of mean depth for site  Temperature Temperature Temperature Parameters Required Initial Condition InitialCond Initial condition initial temperature of the segment or layer (if vertically sCould this system stratify could system vertically stratify Valuation or loading temperature of the segment. can use annual means for ea

stratum and constant or dynamic values 

Wind Wind Wind parameters required 

Initial Condition InitalCond initial wind velocity 10 m above the water Mean Value MeanValue mean wind velocity 
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Wind Loading Wind Wind daily parameter; wind velocity 10 m above the water; ca

default time series, constant or dynamic loadings 

USER INTERFACE INTERNAL TECH DOC DESCRIPTION 

Light Light Light Parameters Required 

Initial Condition Light Light Loading Loadsrec daily parameter; avg. light intensity at segrment top; can 

annual mean, constant loading or dynamic loadings 

Photoperiod Photoperiod Photoperiod fraction of day with daylight; optional, can be calculated 

latitude 

pH pH pH Parameters Required 

Initial Condition InitialCond initial pH value State Variable Valuation pH pH pH of the segment; can choose constant or daily value. Mean alkalinity alkalinity alkalinity mean Gran alkalinity (if dynamic pH option selected) Sand / Silt / Clay TSediment Inorganic Sediment 

Parameters 

If the inorganic sediments model is included AQUATOX, the following parameters are rfor sand, silt, and clay 

Initial Susp. Sed. InitialCond Initial Condition initial condition of the sand, silt, or clay Frac in Bed Seds FracInBed FracSed fraction of the bed that is composed of this inorganic sed

Fractions of sand, silt, and clay must add to 1.0 

Loadings from Inflow Loadings Inflow Loadings daily sediment loading as a result of the inflow of water Loadings from Point Sources Alt_Loadings[Pointsource] Point Source Loadings daily loading from point sources Loadings from Direct Precipitation 

Alt_Loadings[Direct Precip] Direct Precipitation Load daily loading from direct precipitation 

Non-point source loadings Alt_Loadings[NonPointsource] Non-Point Source Loading Daily loading from non-point sources